Underwater exhaust mechanism



Patented Dec. 16, 1930 UNITED STATES PATENT OFFICE FINN T. IRGENS, 0FMILWAUKEE, WISCONSIN, ASSIGNOR TO OUTBOARD MOTORS COR- PORATION, 0FMILWAUKEE, WISCONSIN, A CORPORATION OF MICHIGAN UNDERWATER EXHAUSTMECHANISM Application filed Rbruary 6, 1930. Serial' No, 426,249.

This invention relates to improvements .in under water exhaustmechanism, with par ticular reference to outboard motors.

It is the primary obj ect of the inventionto provide an automatic cutoutfor under water exhausts including. a by-pass port for permitting theexhaust to ass directly into open Y air when the engine 1s started, andmeans for automatically sealing said port when the under water exhaustpassages are freedv of water by operation of the boat. It is my pur-Vpose to accomplish these results with no moving parts and without theuse of valves or like mechanisms by establishing a Water seal for theby-pass port which is rendered eiective by the same means which freesthe under v water exhaust passages of water.

In th drawings:

Figur 1 shows a conventional type vof outboard motor in side elevation,the lower unit of such motor and the exhaust passages being shown invertical axial section. f

Figure 2 is afragmentary detail, in front elevation, of av portion ofthe exhaust manifold shown independently vof the water conduits appliedthereto in Figure 1, andA partially broken away to expose its interiorconstruction. l

Figui-e 3 is a detail view taken in the plane' ence charactersthroughout the several views.

The outboard motor herein illustrated is of conventional design with theexception of the waterseal feature hereinafter to be described. Itincludes an engine having cylinders, of which one is shown at 6,exhausting into a manifold passage .7. The engine operates theusual'drive shaft 8 by which motion is transmitted through the bevelledgearing 9 to a hollow propeller sha-ft 10, carrying a l propeller 11having ports '12 in its blades -cmmunicatingwith the interior of thehol-` low shaft.

The cooling system for the engine is of a RUSS-UEE) leads to-chamber 20in the lower unit which communicates through a duct 21 and the portedplug 22 with the front end of the hollow propel er shaft 10 throughwhich water is exhausted centrifugally by the radialpassages in theblades of propeller 11.

The water circulation system has been`de` scribed briefly in order tobring out the fact that the water seal herein referred to is establishedby means entirely independent of the cooling system. The exhaustconnections and the means for supplying the water seal for the by-passports therein will no.w bedescribed.. I

The exhaust manifold 7 leads through conduit 2A to thechamber 25 in thelower unit which has an outlet at 26 in the form of a flat yrearwardlyextending tube, the delivery end of which Ais preferably located beyondthe propeller 11. The water passing such tube during operation of theoutboard motorinbo'atlpropulsion has an aspirating effect whichwithdraws the gases from the manifold substantially as rapidly as suchgases arrive in the manifold from the engine cylinders. The effect ofthis withdrawal of exhaust gases from the manifold not only eliminatesback pressure therein but actually leaves the interior of the manifoldsubstantially at atmospheric pressure. This condition is obtained,however, only fwhen the de; vice is operating substantially at the fullspeed for which it is designed. At 'lesser speeds there is a lesseraspirating effect at the discharge orifice in the flattened tube 26.

When the engine is started with the motor atrest the chamber 25 willcontainwater to a depth considerably in excess -of that indicated by thewater line shown inv Figure 1, .which is the approximate water lineduring full speed operation on a planing boat. This water will opposeany delivery of exhaust gases through the port at 26. In order to avoidexcessive back pressure it is desirable to provide means for exhaustinggases directly into the atmosphere and for that purpose I have providedby-pass ports 28 which open into-a pipe 29 which communicates at 30 withthe atmosphere. A deilector 3l is preferably associated with port 30 inorder to direct downwardly fluids issuing from such port. e

For the purpose of sealing ports 28 after the normal under water exhaustpassage is opened, as when the outboard motor is operating at full speedin boat propulsion, I provide a means independent of the engine coolingsystem for filling pipe 29 with water, thereby cutting ofilcommunication between ports 28 and port 30. This may be done in numerousways, one of which involves the provision of partition 16 in the lowerunit to form therein a passage 32 opening forwardly through a mouth 33and communicating around bushing 34 with a duct at 35 opening at 36through the wall of conduit 24 and pipe 29 into the interior of suchpipe.

The only force acting to deliver water through the system of passagesjust described is the movement of the outboard motor through a body ofwater which establishes pressure at mouth 33 and tends to evacuate waterthrough the delivery port 26 of the under water exhaust. Both thepressure established in chamber 32 and the depression established inchamber 25 will be, in general, proportioned to the rate of operation ofthe motor and hence it is easily possible to locate ports 28 and 30 atsuch a height that communication therebetween will be sealed by the riseof water in pipe 29 at approximately the same time that the under waterexhaust through the flattened tube 26 becomes effective.

In order to keep the pipe 29 full of water during normal motoroperation, the amount of water supplied to the pipe is preferably suchthat some of the water will flow through port 30. Under suchcircumstances, some of it vmay also flow through t'" ports 28, but thisis immaterial since the amount of such water will be small and thereforewill not destroy theeii'ective sealing of such ports. The pressureconditions existing in thev exhaust manifold during full operation ofthe Y motor will not encourage a loss of sealing water therein and suchloss is reduced also bythe fact that openings 28 are small in diameter,while the combined area is effective for by-passing gases, andresistance to flow of a liquid is greater than would be the case if asingle port of like area were used. It is particularly to be noted thatno loss of Water through ports 28 can affect in any way the coolingsystem for the Amotoresince the sourceof such water is `entirelyindependent of the cooling system. It is also to systemF of which benoted that there are no moving parts such as might become stuck, novalves being used.

1. The combination with a marine engine having an exhaust manifold, witha submersible outlet and an atmospheric by-pass, of means forestablishing a liquid seal for said by-pass.

2. The combination with a marine engine having an exhaust manifold, witha submersible outlet and an atmospheric by-pass, of means forestablishing a liquid seal for said by-pass, and means for freeing saidsubmersible outlet of water accumulated there in, both of said meansbeing dependent for their operation upon movement through a body ofwater, whereby said seal will be established as said outlet is freed ofwater.

3. In an outboard motor, the combination with an engine having aby-passing exhaust manifold and a lower, unit provided with an underwater outlet for said manifold, said lower unitl being provided with aforwardly disposed opening, and a well communicating with said openingand extending across the by-pass of said manifold whereby water admittedthrough said opening as said outboard motor is in movement at apredetermined rate will fill said .well to the point of sealing saidby-pass.

4. In an outboard motor, the combination with an engine having anexhaust manifold provided with a by'pass including a well having exhaustgas inlet and outlet openings, 'of a lower unit provided with asubmersible outlet with which said manifold is in communication, and asubmersible water i t communicating' with said well and opening in adirection to receive water in the movement of said lower Zunit, whereby,at a predetermined rate of movement of said lower unit, to elevate waterinto said well to a depth sufficient to cover one of said openings toseal said by-pass.

5. In an outboard motor, the combination' with an engine having anexhaust 'manifold vprovided with a by-pass including a Well havingexhaust gas mlet and outlet openings, of a lower unit provided with asubmersible outlet with which said manifold is in communication, and aVsubmersible water inlet communicating with said well Vand opening inadirection to receive water in the movement of said lower unit, whereby,at a predetermined rate of movementl of said lower unit, to elevatewater into said well to a depth suihcient to cover one of said openingsto seal said by-pass, said lower unit being provided with a cooling saidduetis entirely independent.

6. In an outboard motor, the combination Withan engine having an exhaustmanifold provlded wlth a submersible outlet and a by-pass duct to openair above water, of a lower unit for said engine including a coolingsystem conduit therefor and a forwardly opening duct independent'of saidconduit and adapted in the movement of said 't tov 5 receive water, saidduct lbeing extended across the by-pass of said manifold whereby waterrising in said duct will act as -a seal for said by-pass.

` 7. In an outboard motor, the combination 10 with an .engine having anexhaust manifold ported above the water level and yprovidedwith anoutlet therebeneath in a rearward direction, whereby movement of themotor through `the water will tend to exhaust gas l5 from said manifold,of a forwardly disposed `water inlet and a conduit connected with saidinlet, extendin across the port of said manifold and vopening 4todischarge water outside of said manifold. o 8. In an outboard motor, thecombination with an engine having an exhaust manifold ported abovev thewater. level and provided with an outlet therebeneath in la rearwarddirection, -whereby movement of the motor 5 through the water will tendto exhaust gas from said manifold, of a forwardly disposed water inletand a conduit connected with said inlet, extending `across the port ofvsaid manifold and opening to discharge water lo outside of saidmanifold, vsaid "conduit in- ;llding a well disposed within said mani-9. In an outboard motor, the combination with an engine having anexhaust manifold :s` ported above the water level and provided with anoutlet .therebeneath in a rearward direction, whereby movement of themotor throughy the water will tend to exhaust gas from 'said manifold,of a forwardly dis- 0 Iposed waterinlet and aconduit connected with saidinlet, extending across the port A of said manifold and opening to,discharge 'water outside of said manifold, and a lower unit connectedwith 'said engine and in which 5 the opening of said duct is formed,said unit being provided with 'a cooling duct leading to said engine andof which said first mentioned duct is independent. v I 10. In anoutboard motor adapted to be u partly submerged to a. predeterminedwater i line, the combination with an en nehaving an exhaust manifoldprovided wlth an outv let below said water line and an atmoshericby-pass therefor above said `water s ine, of a cooling system for ,saidengine, a duct independent of said 'cooling system having an inlet belowsaid' water line and l intercepting said b -pass at a level above saidwater line, an .means effective in the operation of a motor forestablishing a head o water in said duct above said level, whereby toprovide a liguid seal for said by-pass lin the opgration o said motor.

FINN T. IRGENS.

